Use as corrosion inhibitors, nitrogen-heterocyclic phosphonates

ABSTRACT

These compounds which may be characterized as phosphonates of nitrogen-heterocyclics have many uses including their use as biocides, such as bacteriocides, herbicides, corrosion inhibitors, chelating agents, etc.   WHEREIN THE DOTTED LINE REPRESENTS A CYCLIC STRUCTURE WHICH CYCLIC STRUCTURE MAY BE THE SOLE CYCLIC STRUCTURE, OR MAY BE ATTACHED TO OTHER CYCLIC GROUPS. These nitrogen heterocyclic phosphonates are prepared by reacting an aromatic nitrogen-heterocyclic compound, wherein the nitrogen atom is in the form of a quaternary alkoxy derivative (N-OR hereinafter defined) with a phosphite salt, preferably in the form of an ester of the phosphite, as exemplified by the following equation:   Nitrogen-heterocyclic phosphonates wherein the phosphonate group is ortho- or para- to the nitrogen heterocyclic group, where the compounds are characterized as follows:

United States Patent [191 Redmore Nov. 27, 1973 USE AS CORROSIONINHIBITORS,

NITROGEN-HETEROCYCLIC PHOSPHONATES Derek Redmore, Ballwin, Mo.

[75] Inventor:

[73] Petrolite Corporation, Wilmington,

Del.

Filed: Aug. 19, 1971 Appl. No.: 173,296

Assignee:

Related U.S. Application Data Division of Ser. No. 801,856, Feb. 24,1969, Pat. No. 3,673,]96. Y

U.S. Cl. 21/25 A, 2l/2.7 A, 106/14, 252/8.55 E, 252/148, 252/389 A,260/297 P Int. Cl. C23f 11/16, C23f 11/04 Field of Search 252/389 A,8.55 E, 252/146, 148, 151; 21/27 A, 2.5 A; 260/297 References CitedUNITED STATES PATENTS ll/l965 Lorenz et al. 252/283 P 5/1972 Redmore252/389 A 6/1972 Redmore 252/389Z Primary Examiner-Leon D. RosdolAssistant Examiner-Irwin Gluck Anorney-Sidney B. Ring [57] ABSTRACTNitrogen-heterocyclic phosphonates wherein the phosphonate group isorthoor parato the nitrogen heterocyclic group, where the compounds arecharacterized as follows:

N (para substituted) wherein the dotted line represents a cyclicstructure which cyclic structure may be the sole cyclic structure, ormay be attached to other cyclic groups.

These compounds which may be characterized as phosphonates ofnitrogen-heterocyclics have many uses including their ,use as biocides,such as bacteriocides, herbicides, corrosion inhibitors, chelatingagents, etc.

5 Claims, No Drawings 1 USE AS CORROSION INHIBITORS,

NITROGEN-HETEROCYCLIC PHOSPHONATES Division of my application Ser. No.801,856 filed Feb. 24, 1969 now US. Pat. 3,673,196.

This invention relates to nitrogen-heterocyclic phosphonates. Moreparticularly this invention relates to nitrogen-heterocyclicphosphonates wherein the phosphonate group is ortho or para to theheterocyclic nitrogen group. Still more particularly, this inventionrelates to compounds characterized by the following groups:

(para substituted) wherein the dotted lines indicate a cyclic structure,which cyclic structure may be the sole cyclic structure or may beattached to other cyclic groups. These compounds may be characterized asphosphonates of nitrogen heterocyclics.

This invention also relates to the preparation of these phosphonateswhich comprises reacting an aromatic nitrogen-heterocyclic, wherein thenitrogen atom is in the form of a quaternary alkoxy derivative (N-OR),with a phosphite salt, preferably in the form of an ester of thephosphite, as exemplified by the following equation:

This invention also relates to uses for these com pounds for example asbiocides, such as bacteriocides, herbicides. corrosion inhibitors.chelating agents, etc.

in my Application Ser. No. 733.328 filed May 31. 1968, now abandonedthere are described and claimed processes for preparing dihydro nitrogenheterocyclic phosphonates and the resulting phosphonates which aresubstituted ortho and/or para to the heterocyclic nitrogen atom, etc.For example, the invention of Ser. No. 733,328 may be illustrated by thefollowing equa tions:

R R R R R R may be hydrogen or a substituted group, for example, alkyl,cycloalkyl, aryl, alkaryl, aralkyl, etc.

R is an ester moiety for example alkyl, aryl, cycloalkyl, aralkyl,alkaryl, etc. oxyalkylated groups, etc.

The groups of R to R may also be further substituted provided thesubstituted groups do not interfere with the reaction.

X is any suitable anion, for example, halogen, e.g. chlorine, bromine,iodine, etc., 80 R, -SO R where R isalkyl, etc., such as -SO.,Me, -SO'Et,

R USOQ etc.

The present invention relates to a process of preparaing analogousnitrogen heterocyclic phosphonates as contrasted to thedihydro-heterocyclic phosphonates of Ser. No. 733,328 (i.e., fullheterocyclic as contrasted to dihydro-heterocyclic).

The present invention may be illustrated by the following equations:

(where R; is hydrogen) where R is a hydrocarbon group such as alkyl,cycloalkyl, aryl. aralkyl, alkaryl. etc, R5, R R R... R6 is hydrogen ora substituted group. for example. alkyl, cycloalityl. eryl. alkaryl.aralkyl, etc.

R1 is an ester moiety for example alkyl, aryl. cyeloalkyl. aralkyl.alkaryl. etc. oxyalkylated groups. etc.

The groups of R, to K, may also be further when tuted provided thesubstituted groups do not interfere with the reaction.

X is any suitable anion. for example. halogen. e.g. chlorine. bromine.iodine. etc.. R. -SO R. where R is alkyl, such as .-SO Me. -SO.Et,

RUSOB etc.

It is to be noted that in the invention described in Ser; No. 733,328the R, group remains affixed to the heterocyclic nitrogen throughout thereaction and in the final product, thus yielding a dihydro derivative ofa heterocyclic compound; whereas in the present invention the nitrogenbonded OR, group is removed as an alcohol moiety during the reaction toyield the heterocyclic compound itself.

In preparing the compounds of this invention it is convenient to startwith nitrogen-heterocyclic compound, oxidize it to the N-oxide, reactthis with an alkyl ester of an inorganic acid such as alkyl halide,alkyl sulfate, etc. to form the OR group, and to then react the salt ofa phosphite ester to yield the heterocyclic phosphonate as illustratedby the following series of reactions:

Any nitrogen heterocyclic having an available ortho and/or para positioncapable of being activated by quaternary formation of the nitrogen groupwith an -OR group so as to promote reaction with salts of phosphiteesters can be employed. This includes heterocyclics having one or morerings, where at least one ring has a nitrogen heterocyclic group and theother rings are carbocyclic or heterocyclic, i.e., they may containoxygen or other non-carbon elements in the ring, etc. for example,

N etc.

The above ring systems may also be substituted. The adjacent rings mayalso contain heterocyclic groups for example oxygen, nitrogen, etc.,and/or may contain rings having less than six molecules in the ring forexample a 5 member ring.

In certain instances more than one nitrogen heterocyclic ring may becapable of reacting with the phosphite salt so that phosphonatesubstitution may occur in more than one ring.

X is any suitable anion, for example, halogen, e.g. chlorine, bromine,iodine, etc., -SO.R, -SO R where R is alkyl such as Representativeexamples of heterocyclic reactants include pyridines and benzoanddibenzoderivatives of pyridine, for example, pyridine, alkylatedpyridines such as Z-picoline, 3-picoline, 4-picoline, etc., 2,4-lutidine, 2,6-lutidine, 2,3-lutidine, etc., collidines, etc. quinolineand alkylated qunilines, etc. isoquinolines, and alkylatedisoquinolines, etc. phenanthridines, and substituted phenanthridines,etc., acridines and substituted acridines, etc.

The nitrogen group in the heterocyclic ring is reacted with aquaternizing agent to activate the ring.

The phosphorous-containing reactant is a metal salt of phosphorous acid,preferably in the form of an alkali metal salt in which the metal isdirectly bonded to phosphorous. In order to prevent undesirable sidereactions the phorphorous acid is used in the form of a derivative,preferably as a diester.

Where the phosphite ester contains more than one phosphite unit, aplurality of heterocyclic units may be joined thereto, for example Ingeneral, the reaction is carried out in an inert solvent which is waterfree at a temperature and time sufficient to promote the desiredreaction. Ether solvents such as diethyl ether, dioxane andtetrahydrofuran are useful as well as aromatic hydrocarbon solvent likebenzene, toluene, etc. Particularly useful are dipolar aprotic solventssuch as dimcthyl sulfoxide, dimethyl formamide N-methyl pyrrolidone.Combinations of these various types of solvents can also beadvantageously used. Temperature and time are interrelated. Thus, atemperature of from 30 to the decomposition temperature of reactants andproducts can be employed, the upper limit of temperature being generallyabout 150 C., for a time of from 0.5 hours but preferably 1 3 hours. Theinorganic salt is separated from the organic layer by filtration or bywater extraction and the phosphonate derivative is separated from theorganic layerQln addition the reaction is best carried out on an inertatmosphere such as nitrogen, argon, etc. In this way the attack ofoxygen on phosphite salts and on the products is prevented.

The following examplesv are presented by way of illustration and not oflimitation.

EXAMPLE 1 Diethyl Pyridine 2-phosphonate To pyridine N-oxide (19g; 0.2mole) was added dimethyl sulfate (25.2g; 0.2 mole) during 30 minutes.The reaction was completed by heating at 100 C. for 2 hours yieldingN-methoxy pyridinium methosulfate. Diethyl sodio phosphonate wasprepared by dissolving sodium (4.6g; 0.2 mole) in a solution of diethylphosphite (27.6g; 0.2 mole) in dioxane (100 ml) in an argon atmosphere.The N-methoxy pyridinium quaternary was suspended in toluene by stirringwhile the diethyl sodio phosphonate solution was added. The reactionflask was cooled to maintain the temperature at 25 35 C. After stirringfor 1 hours water (100 ml) was added and the organic product isolated bychloroform extraction. Evaporation of the chloroform extract anddistillation yielded diethyl pyridine-Z-phosphonate with a small amountof diethyl pyridine 4-phosphonate. Yield 14g (33 percent) bp 140 8 C./1.5 mm. The presence of the two isomers was established by infraredabsorption; 2-isomer 13.311 (strong, 4 adjacent hydrogen) and 4.isomer,12.3 .4 (weak, 2 adjacent hydrogen).

prepared from 4-picoline-N-oxide (54.4g; 0.5 mole) and dimethyl sulfate(63g; 0.5 mole) and suspended by stirring with toluene (250 ml). To thissuspension was added diethyl sodio phosphonate in dioxane (150 ml)prepared from diethyl phosphite (69g; 0.5 mole) and sodium (11.5g; 0.5mole). This addition was carried out in 40 minutes during which time thetemperature was controlled at 45 C. by cooling. After stirring for onehour water was added to the reaction and the product isolated bychloroform extraction. Evaporation and distillation yielded diethyl4-methyl pyridine-2- phosphonate 17g; bp 109-l l20.05 mm. The infraredspectrum shows absorption at 7.97 p. (P#)), 9.8 p. and 10.4 p. (P-O-C).

. EXAMPLE 3 Diethyl Quinoline-Z-Phosphonate and -4-PhosphonateN-methoxyquinolinium methosulfate was prepared from quinoline N-oxide(50g; 0.344 mole) and dimethyl sulfate (43.5g; 0.344'mole). To thisquaternary was added diethyl sodiophosphonate from diethyl phosphite(47.5g; 0.344 mole) and sodium (7.9g; 0.344 mole) in dioxane ml.). Thereaction was completed by heating at 100 110 C. for two hours.

Water was added to the reaction, after cooling, and the product wasisolated by benzene extraction. Evaporation'of the solvent and heatingunder vacuum at 140 C./2 mm gave a residue which was a mixture ofdiethyl quinoline 2-phosphonate and 4-phosphonate.'Analysis found N 5.4percent calculated N. 5.28 percent.

EXAMPLE 4 Diethyl lsoquinoline -1- Phosphonate .N-methoxy isoquinoliniummethosulfate was converted by reaction with diethyl sodio phosphonate indioxane into diethyl isoquinoline-l-phosphonate in 30 percent yieldusing the procedure of Example 3. The product was purified bydistillation bp C./O.l5 mm.

EXAMPLE 5 Diethyl 4-Cyanopyridine -2- Phosphonate EXAMPLE 6 4-MethylPyridine -2- Phosphonic Acid Diethyl 4methyl pyridine -2-phosphonate ('1lg.) (The product from Example 2) was heated for six hours with 18percent hydrochloric acid (120 ml) at 100. The acid was removed undervacuum to leavea gum which was dissolved in ethyl alcohol. Addition ofether yielded white crystals which after drying gave pure 4- methylphyridine-Z-phosphonic acid (7.2g; 86 percent) mp 272-6 C.

Analysis Calculated C, 41.62, H, 5.78, N. 8.09, P, [7.92 percent FoundC, 41.65; ,H,4.63/;;H, 8.09; P, 16.95 percent EXAMPLE 7 Quinoline 2- and-4- Phosphonic Acids The product of Example 3 (7.7g) was heated underreflux for 346 hours with 18 percent hydrochloric acid (60 ml.). Usingthe isolation procedure of Example 6 a crude quinoline phosphonic acidg. (82 percent) was isolated. Crystallization from acetic acid gave purequinoline -2- phosphonic acid mp 200 C.

Analysis Calculated N, 6.70 percent; P, 14.83 percent.

Found N, 6.33 percent; P, 14.71 percent.

As is quite evident, other nitrogen heterocyclics and phosphites areuseful in my invention. It is, therefore, not only impossible to attempta comprehensive catalogue of such compounds, but to attempt to describethe invention in its broader aspects in terms of specific heterocyclicsand phosphites reacted would be too voluminous and unnecessary since oneskilled in the art could by following the description of the inventionherein select a useful reactant. This invention lies in the reaction ofsuitable heterocyclics and phosphites and their individual compositionsare important only in the sense that they react to form useful products.To precisely define each specific useful heterocyclic in light of thepresent disclosure would merely call for chemical knowledge within theskill of the art in a manner analogous to a mechanical engineer whoprescribes in the construction of a machine the proper materials and theproper dimensions thereof. From the description in this specificationand with the knowledge of a chemist, one will know or deduce withconfidence the applicability of specific heterocyclics suitable for thisinvention. In analogy to the case of a'machine, wherein the use ofcertain materials of construction or dimensions of parts would lead tono practical useful result, various materials will be rejected asinapplicable where others would be operative. I can obviously assumethat no one will wish to use a useless heterocyclic nor will be misledbecause it is possible to misapply the teachings of the presentdisclosure to do so. Thus, any heterocyclic that can react as statedherein can be employed similarly any nitrogen heterocyclic phosphonatewhich is within the scope of this invention and effective as a corrosioninhibitor (as hereinafter stated) is within the scope of this invention.

USE AS CORROSION INHIBITORS This phase of this invention relates to theuse of the present compounds in inhibiting the corrosion of metals, mostparticularly iron, steel and ferrous alloys. These compounds can be usedin a wide variety of applications and systems where iron, steel andferrous alloys are affected by corrosion. They may be employed forinhibiting corrosion in processes which require this containing medium,as, for example, in oil wells pro- I ducing corrosive oil or oil-brinemixtures, in refineries, and the like. These inhibitors may, however, beused in other systems or applications. They appear to possess propertieswhich impart to metals resistance to attack by a variety of corrosiveagents, such as brines, weak inorganic acids, organic acids, CO H38,etc.

The method of carrying out this process is relatively simple inprinciple. The corrosion preventive reagent is dissolved in the liquidcorrosive medium in small amounts and is thus kept in contact with themetal surface to be protected. Alternatively, the corrosion inhibitormay be applied first to the metal surface, either as is, or as asolution in some carrier liquid or paste. Continuous application, as inthe corrosive solution, is the preferred method, however.

The present process finds particular utility in the protection of metalequipment of oil and gas wells, especially those containing or producingan acidic constituent such as H S, CO organic acids and the like. Forthe protection of such wells, the reagent, either undiluted or dissolvedin a suitable solvent, is fed down the annulus of the well between thecasing and the producing tubing where it becomes comingled with thefluid in the well and is pumped or flowed from the well with thesefluids, thus contacting the inner wall of the easing, the outer and theinner wall of tubing, and the inner surface of all wellhead fittings,connections and flow lines handling the corrosive fluid.

Where the inhibitor composition is a liquid, it is conventionally fedinto the well annulus by means of a motor driven chemical injector pump,or it may be dumped periodically (e.g., once every day or two) into theannulus by means of a so-called bole weevil device or similararrangement. Where the inhibitor is a solid, it may be dropped into thewell as a solid lump or stock, it may be blown in as a powder with gas,or it may be washed in with a small stream of the well fluids or otherliquid. Where there is gas pressure on the casing, it is necessary, ofcourse, to employ any of these treating methods through a pressureequalizing chamber equipped to allow introduction of reagent into thechamber equalization of pressure between chamber and casing, and travelof reagent from chamber to well casing.

Occasionally, oil and gas wells are completed in such a manner thatthere is no opeening between the annulus and the bottom of the tubing orpump. This results, for example, when the tubing is surrounded at somepoint by a packing held by the casing or earth formation below by thecasing. In such wells the reagent may be introduced into the tubingthrough a pressure equalizing vessel, after stopping the flow of fluids.After being so treated the well should be left closed in for a period oftime sufficient to permit the reagent to drop to the bottom of the well.

For injection into the well annulus, the corrosion inhibitor is usuallyemployed as a solution in a suitable solvent. The selection of solventwill depend much upon the exact reagent being used and its solubilitycharacteristics.

For treating wells with packed-off tubing, the use of solid sticks" orplugs of inhibitor is especially convenient. These may be prepared byblending the inhibitor with a mineral wax, asphalt or resin in aproportion sufficient to give a moderately hard and high-melting solidwhich can be handled and fed into the well conveniently.

The protective action of the herein described reagents appears to bemaintained for an appreciable time I after treatment ceases, buteventually is lost unless another application is made.

For example, for the protection of gaswells and gascondensate wells, theamount of corrosion inhibitor used might range between about V4 to 3lbs. more per million cubic feet of gas produced, depending upon theamounts and composition of corrosive agents in the gas and the amount ofliquid hydrocarbon and water produced. However, in no case does theamount of inhibitor required appear to be stoichiometrically related toThese compounds can also be used in the-prevention.

of corrosion in the secondary recovery of petroleum by water floodingand in the disposal ofwaste water and brine from oil and gas wells.Still more particularly,

they can be used in a process :of preventingzcorrosionin water floodingand in the disposal of waste water and brine from oil and gas wellswhich ischaracterized by injecting into an underground formation anaqueoussolution containingminor amounts of the compositions of thisinvention, in sufficient amounts to prevent'the:

corrosion of metals employed in such operation.

When an oil well ceases to flowby thenatural pressure in the formationand/or substantial quantities of oil can no longer be obtained bytheusual pumpingmethods, various processes are sometimes used for the.treatment of the oil-bearing formationin order to increase the flow ofoil. These processes are usually described as secondary recoveryprocesses. One such process which is used quitefrequently is thewaterflooding process wherein water is pumped under pressurezinto what iscalled an injection well and oil, alongwith quantities of water, thathave been displaced from the formation, are pumped out of anadjacent'well'usually referred to as a producing well. The oil which ispumped from the producing well is then separated from the water that hasbeen'pumped from the producing well and the water is pumped to a-storagereservoir from which it can again be pumped into theinjection well.Supplementary water from other sourcesmay also be used in conjunctionwith the produced water. When the storage reservoir is open to theatmosphere and the oil is subject to aeration this type'of waterflooding sys tem is referred-to herein as an open water flooding system.If the water is'recirculated ina closed system pair and replace suchequipment at frequent intervals.

These compositions can be employed in preventing. corrosion in systemscontaining. a corrosive aqueous media, and most particularly in systemscontaining brine, which is characterized by employingthe phosphonatecompounds described herein. For example,

10 and particularly those containing iron, steel, and ferrous alloys,such process being characterized by employing in water flood operationan aqueous solution of the compositions of this invention.

lnmany oil fields large volumes of water are produced and must bedisposedof where water flooding operations are notin use of wherewaterfloodingoperations-cannot handle the amount of produced water. MostStates have laws restricting pollution of streams and land with'producedwaters, andoil producers must thenfind some 'methodof disposingof thewaste producedsalt water. in many instances therefore, the salt water isdisposed by injecting-the water into permeablelow pressurestratab'elowthe fresh water level. Theformation intox-which the water isinjected is not the oil producing formation andthis type of disposal isdefined as salt water disposal or wasterwater disposal. The;

problems of corrosion of equipmentareianalogous to those encountered inthe secondary recovery operation by flooding. The compositionsofthis-invention can also be used in-such water disposal wells thusproviding a simpleand economical. method of solvingthe corro-- sionproblems encountered in disposing of unwanted. water.

Water flood and waste disposal operations are too well knowntorequirefurther elaboration. In essence, the floodingoperation iseffected in the. conventional manner except that the flooding mediumcontains a minoramount of-these compounds, sufficient to preventcorrosion.

While'the-flooding medium employed insaccordance with-thepresentinvention containswater oroil field brine and-the-compounds ofthis invention, the medium may also contain. other materials. Forexample, the flooding medium'may also contain other agents such assurfaeeactiveagentsor detergents which aid in wetting,

compound, theparticular' system, etc. Concentrations.

of at least about 0.25ppm, such as about 0.75 to 7,500 ppm. for exampleabout 1 to 5,000 ppm, advantageously about .10 to 1,000 ppm,.butpreferably about 15 250 ppm may be employed. Larger amounts can also beemployed such as 1.5-5.0 percent although there is generally nocommercial advantage in so doing.

For example, since the success' of a water flooding operation manifestlydependsupon its total cost being less than-the value of the additionaloil recovered from. theoil reservoir, it is quite important touse aslittle as possibleof these compounds-consistent withzoptimum corrosioninhibition.

Since these compounds are themselves'inexpens'ive and are used in lowconcentrations, they enhance the success of a flood operationbyloweringv the cost" thereof.

By varying the constituents of the composition, the compounds of thisinvention can be made more. oil or more water soluble, depending onwhether the composition is to be employed in oil or water systems.

These compounds can also be employed in conjunction with other corrosioninhibitors, for example, of the film-forming type. Non-limiting examplesinclude the acylated polyamines such as described in US. Patents Re.23,227, 2,466,517, 2,468,163, 2,598,213 and 2,640,029. These acylatedpolyamines may be described as amides, imidazolines,tetrahydropyrimidines, etc.

EXAMPLES The heterocyclic phosphonates of this invention, particularlythose of Examples 1 through 7, when tested exhibited corrosioninhibiting properties.

OTHER USES 7. as anti-static agents for textile, plastics, etc.

8. as lube oil additives 9. as emulsifiers for insecticidal andagricultural com positions 10. as flocculants, particularly as flocaidsl 1. scale inhibitors.

I claim:

L A process of inhibiting corrosion which is charac terized by treatinga metal with a composition of full nitrogen heterocyclic phosphonates ormixtures thereof or phosphonic acid derivatives thereof wherein thenitrogen heterocyclic group is a pyridine group having an unsaturatedbond between the nitrogen atom and one adjacent carbon atom and asaturated bond between the nitrogen atom and the other adjacent carbonatom and the phosphorus atom of a phosphonate group is bonded directlyto a carbon atom of the pyridine group and a phosphonate group is orthoor para to the nitrogen atom in a pyridine group.

2. The process of claim 1 wherein the composition is a mixtureconsisting essentially of diethyl pyridine-2' phosphonate and diethylpyridine-4-phosphonate.

3. The process of claim 1 wherein the composition is diethyl 4-methylpyridine-2-phosphonate.

4. The process of claim 1 wherein the composition is diethyl4-cyanopyridine-2-phosphonate.

5. The process of claim 1 wherein the composition is 4-methylpyridine-2-phosphonic acid.

2. The process of claim 1 wherein the composition is a mixtureconsisting essentially of diethyl pyridine-2-phosphonate and diethylpyridine-4-phosphonate.
 3. The process of claim 1 wherein thecomposition is diethyl 4-methyl pyridine-2-phosphonate.
 4. The processof claim 1 wherein the composition is diethyl4-cyanopyridine-2-phosphonate.
 5. The process of claim 1 wherein thecomposition is 4-methyl pyridine-2-phosphonic acid.